Exhaust tubulation seal having a reduced width



July 20, 1965 R. P. WATSON EXHAUST TUBULATION SEAL HAVING A REDUCED WIDTH Filed May 25, 1960 INVV'HEXNTOR: ROBERT P. WATSON,

Hl ATTORNEY;

United States Patent 0 3,1963% EXHAUST TUBULATHON SEAL HAVENG A REDUCED WIDTH Robert P. Watson, chenectady, N.Y., assignor to General Electric Company, a corporation of New York Filed May 23, 3350, Ser. No. 30,965 6 Claims. (61. 313-317) My invention relates to electric discharge devices and pertains more particularly to a new and improved electric discharge device including a new and improved exhaust tubulation therefor and new and improved methods of sealing a tabulation and processing an electric discharge device.

In the art of manufacturing electric discharge devices and similar other enveloped devices it is a common practice to afiix a metal tubulation to the envelope or" the device for exhausting or gas charging purposes. Following exhaust or gas charging of the device through the tubulation the device including the tubulation is customarily sealed by pinching the end of the tube to eifect a fusion or cold weld of the opposite sides of the tube. This manner of sealing the end of the tubulation results in a flared end which is invariably substantially wider than the normal outside diameter of the tubulation. Such a flare presents difliculty in fitting another member over or on the end of the tubulati-on. For example, in some electric discharge devices the tubulation is ordinarily sealed in an anode lock and it is desirable to fit a heat radiator over the tubulation to effect dissipation of heat from the anode and to protect the tubulation from damage thus to avoid leakage. In such an arrangement it is also desirable that the radiator be rigidly fitted in place. When the tubulation end is flared by the pinch oft step to a width greater than the normal outside diameter of the tubulation, it is difiicult to fit a radiator thereover without providing an oversized bore to enable insertion therein of the flared tubulation end. Also, in such an arrangement it is not possible to lit the bored radiator tightly over the tubulation, and fastening means must be provided to hold the radiator tightly on the anode block. Additionally, and also by way of example, in some devices it is desirable to use the tubulation as an anode contact. When the tubulation end is flared in the above-discussed manner by a sealing pinch-off step it is difiicult, if not impossible, to fit an electrical connector over the end of the tabulation.

Accordingly, a primary object of my invention is to provide a new and improved pinched-01f tubulation construction.

Another object of my invention is to provide a new and improved method of effecting the sealing of a tubulation.

Another object of my invention is to provide a new and improved electric discharge device including an improved exhaust tubulation arrangement.

Another object of my invention is to provide a new and improved method of processing an electric discharge device.

Another object of my invention is to provide a new and improved electrical contact arrangement for an electric discharge device.

Further objects and advantages of my invention will become apparent as the following description proceeds and the features of novelty which characterize my invenhldfifidli Patented July 20, 1%65 tion will be pointed out with particularity in the claims annexed to and forming part of this specification.

In carrying out the objects of my invention I provide an electric discharge device including a reentrant anode block. The anode block includes an exhaust passage and fitted in the block to communicate with the passage is a metal exhaust tribulation. The diameter of the end portion of the tubulation is reduced and the extreme end is pinched with the width of the pinched portion no greater than the normal outer diameter of the tubulation. Tightly fitted over the tubulation and engaging it over the length of the normal outer diameter portion thereof is a member having an inner diameter approximately the same as the normal outer diameter or" the tribulation. This member can comprise either a heat radiator or an annular electrical connector. In manufacturing the device, a straight-walled tubulation is provided and fluid is drawn through the tabulation in the exhaust or gas charging of the device. Then the device is pinched oil at a point outwardly spaced from the desired finished seal. Subsequently, the tubulation is reduced in diameter intermediate the pinch oh and the device. Then a final pinch off is effected in the reduced-diameter region thus to provide the desired narrow-width flare.

For a better understanding of my invention reference may be had to the accompanying drawing in which:

FIGURE 1 is an enlarged fragmentary sectional view of an electric discharge device incorporating an embodiment of my invention;

FIGURE 2 is an enlarged fragmentary view illustrating a modified form of my invention; and

FIGURES 3-5 are enlarged fragmentary views illustrating the various steps in constructing a tubulatlon in accordance with a feature of my invention.

Referring to the drawing, there is shown in FIGURE 1 an electric discharge device of the planar electrode type generally designated 1 and incorporating an embodiment of my invention. The device It includes an evacuated envelope 2 comprising a plurality of stacked annular ceramic and metal members comprising wall sections and annular contacts adapted for making electrical connections to a plurality of spaced cooperating electrode elements contained in the envelope and shown in outline.

One of the mentioned electrode elements is an anode 3 which can comprise a cylindrical metal block extending through the upper end Wml of the envelope and including an active portion disposed in the envelope. The anode block 3 is provided with a central exhaust passage 4 which can communicate with the interior of the envelope by extending through the active inner end of the anode block, as shown, or, alternatively, by communicating with a transverse passage opening on the lateral surfaces of the anode internally of the envelope.

The upper end of the anode 3 is counterbored and has tightly fitted and bonded therein an end of a metal exhaust tabulation 5. The tubulation 5 includes a protruding portion the end 6 of which is reduced in diameter relative to the normal outside diameter of the tubulation. At the reduced portion 6 is provided a pinched oif seal or cold weld 7. The pinched off seal '7 constitutes a flared chisellike end. However, as seen in FIGURE 1 the width of the pinched ofr" end '7 is no greater than the normal outside diameter of the tabulation 5 and is preferably substantially less than the normal outside diameter of the tribulation.

sneaeoe 33 Fitted over the tubulation is a heat radiator 8 which can comprisea block of high heat conducting material. The radiator 8 includes a bottomed central bore 1% and a counterbore 11. The diameter of the bore 19 is such as to fit tightly over the portion of the tubulation 5, protruding from the end of the block and having the normal outside diameter, and the diameter of the counterbore 11 is such as to fit tightly over the outer end of the anode block. In this arrangement the narrow width of the pinch off or cold weld flare 7 presents no obstacle to the fitting of the radiator over the tubulation. Also, because the flared end 7 is narrower than the normal outer diameterof the tubulation, the bore in the radiator need not be enlarged to fit over the flare and, thus, the inner diameter of the bore 10 can be desirably dimensioned for tightly fitting the tubulation which serves to rigidize the mounting of the radiator on the device. e

Illustrated in FIGURE 2 is a form of my invention applied to a device in which the tubulation 5 is utilized as an electrical contact. The tabulation of FIGURE 2 can be identical in structure to that described above in regard to FIGURE 1, and identical features bear identical numerals. However, instead of having a radiator fitted thereover, the tubulation of FIGURE 2 is fitted with a contact cap or connector 12 which can be cup-like and have a lead 13 connected thereto. The cap 12 is sufiicient- 1y deep such that when fitted on the end of the tubulation the side wall of the cap extends beyond the flared end '7 and engages the tubulation for a substantial distance over the normal outside diameter region. In this form of my invention the inside diameter of the cap 12 approximates the normal outside diameter of the tabulation such as to fit tightly on the tubulation. If the flared end 7 were wider than the normal outside diameter of the tubulation, as found in the prior art, the fitting of a cap 12 upon the end of the tubulation in the manner shown in FIGURE 2 would be impossible.

In manufacturing a device incorporating my invention one starts with an enveloped device of the type illustrated, for example, in FIGURE 1 and including a uniformly straight-walled metal tubulation. Then the device is processed, as for example, by evacuating or charging the envelope with gas through the tubulation. Followi-n g such processing, the tubulation is pinched off or cold welded at 15 which is at a point on the tubulation outward from the region at which it is desired to have a final pinch off 7 located; The pinch off 15 constitutes a first cold weld and, as see-n in FIGURE 3, is of the usual prior art type which is wider than the normal outside diameter of the tubulation. Such a pinch oir would make impossible the fitting of a radiator or electrical connector cap of the types shown in FIGURES l and 2, respectively, .over the end of the tubulation. Therefore, following the first pin-ch off 3.5 1 reduce the diameter of the tubulation intermediate the pinch off 15 and the inner end of the tubulation by swaging which can be effectively accomplished by passing the region of the tubulation to be reduced in a diameter between a pair of oppositely rotating swaging dies 16 of predetermined width. This operation reduces the diameter of the tubulation in a manner shown in FIGURE 4, and following such reduction of diameter a second pinch ofi of the tubulation is effected in the region of reduced diameter in the manner shown in FIGURE 5. Thus, a second cold,

Weld is effected in the reduced region which is narrower than the normal outside diameter of the tubulation. The tubulation is cut at the dot and dash line 17,.whi'ch is located outwardly of the cold weld 7, by the second pinch off. That is, during the exhaust step it is desirable that v the tubulation not be necked down or reduced in diameter since this would reduce the pumping or exhausting rate capacity of the tubulation. In my method the necking down of the tubulation to enable the formation of the har row width pinch oil takes place after the exhaust process is completed and thus makes available the large inside diameter of the tubulation throughout the whole length thereof for maximum pumping capacity.

Also, it is to be understood from the foregoing that while I have referred to the improved pinch off of my invention as being narrower in width than the normal outside diameter of the tubulation, in some devices the width of the pinch off need not be actually narrower but will be suificient if it i-s no greater than the normal outside diameter of the tubulation.

While I have shown and described specific embodiments of my invention I do not desire my invention to be limited to the particular forms shown and described, and I intend by the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim' as new and desire to secure by Le ers Patent of the United States is: 7 p

1. An electric discharge device comprising an open anode, an exhaust passage extending normal to the active surface thereof, an exhaust tubulation having a first portion sealed in the exterior portion of said exhaust passage and a second portion of a reduced diameter relative to said first portion projecting beyond said passage having the wall thereof pinched ofl forming a gas-tight seal for said tubulation, the major width of said pinched-off portion being no greater than the outside diameter of said first portion.

2. A discharge device according to claim I, wherein the major width of said second portion is substantially less than the outside diameter of said first portion.

3. An electric discharge device comprising an envelope,

an anode, an exhaust passage extending the-rethrough and communicating with the interior of said envelope, a metal tubulation having a first portion sealed in the exterior portion of said exhaust passage and a second portion of a reduced diameter relative to said first portion projecting outwardly of said passage, and a gas-tight pinch-off seal in said second portion having a major width no greater than the outside diameter of saidfirst portion.

' d. An electric discharge device comprising an envelope, an anode block sealed in the wall of said envelope and having a portion extending therefrom including a passage communicating with the interior of the said envelope, a metal tubulation having a first portion sealed in said passage and extending from the upper end of said anode block, said tubulation having a second portion of reduced diameter relative to the said first portion of said tubulation and a gas-tight pinched-off seal in said portion'of reduced diameter, said seal having a major width no greater than the outside diameter of said first portion, and a heat radiator having a central bore and a counter-bore, said radiator being fitted over said tubulation and anode block with the walls of said bore and counteroore tightly embracing said tubulation and anode block, respectively.

5. An electric discharge device comprising an envelope, an electrode having a planar active surface in said envelope, a metal tubulation having a first portion sealed in the wall of said envelope and constituting a contact for said electrode, said tubulation having a second portion of reduced diameter relative to the normal outside diameter of said tubulation and a gas-tight pinched-oft seal in said portion of reduced diameter, said seal having a major width no greater than said outside diameter of said first portion, and a cup-like electrical contact cap fitted over said seal, said cap having a length and inside diameter effective for providing a tight fit between at least the rim of said cap and a part of said first portion.

6. The electric discharge device as in claim 3, further comprising a metal member including a bore having a References Citerl by the Examiner UNITED STATES PATENTS 323,150 7/85 Holzer 316-18 2,367,331 1/45 Bondley 313317X Walker 316-18 Wolf 313-44 Berkey et a1 313-317 X Clark 313-44 Deri 313-44 Manfredi 313-44 DAVID J. GALVIN, Primary Examiner.

RALPH G. NILSEN, Examiner. 

1. AN ELECTRIC DISCHARGE DEVICE COMPRISING AN OPEN ANODE, AN EXHAUST PASSAGE EXTENDING NORMAL TO THE ACTIVE SURFACE THEREOF, AN EXHAUST TUBULATION HAVING A FIRST PORTION SEALED IN THE EXTERIOR PORTION OF SAID EXHAUST PASSAGE AND A SECOND PORTION OF A REDUCED DIAMETER RELATIVE TO SAID FIRST PORTION PROJECTING BEYONE SAID PASSAGE HAVING THE WALL THEREOF PINCHED OFF FORMING A GAS-TIGHT SEAL FOR SAID TUBULATION, THE MAJOR WIDTH OF SAID PINCHED-OFF PORTION BEING NO GREATER THAN THE OUTSIDE DIAMETER OF SAID FIRST PORTION. 